1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Finding max/min of 3d graphs with chain rule

  1. Mar 31, 2008 #1

    can someone please help me on problem number 2 of the link above?
    apologies for the bad handwriting. my professor is just horrible with that.

    i've done max and min with multivariables before and ive done chain rule , but i've never combined the two. also, in that problem, the only critical point seems to be a saddle point, so i'm not sure what the "lowest" point is referring to
  2. jcsd
  3. Mar 31, 2008 #2


    User Avatar
    Staff Emeritus
    Science Advisor

    You don't need to use the chain rule- in fact you don't need to worry about multi-variables at all. Replace x and y in z(x,y) with their expressions in terms of t and differentiate with respect to t. There are two critical points. One is a minimum and the other a maximum.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Finding max/min of 3d graphs with chain rule
  1. Chain Rule (Replies: 30)

  2. Chain Rule (Replies: 25)

  3. Chain rule. (Replies: 6)

  4. The Chain Rule (Replies: 3)